The National Heart, Lung, and Blood Institute sponsored national telephone surveys of practicing physicians in 1983 (N = 1610) and 1986 (N = 1277) to assess attitudes and practices regarding elevated serum cholesterol levels. The 1983 survey was conducted just before the release of the results of the Lipid Research Clinics Coronary Primary Prevention Trial, which showed that a reduction in the blood cholesterol level reduced coronary heart disease. In 1986, 64% of physicians thought that reducing high blood cholesterol levels would have a large effect on heart disease, up considerably from 39% in 1983. Whereas in 1983, physicians attributed considerably less preventive value to reducing the cholesterol level than to reducing blood pressure or smoking, this disparity was substantially smaller in 1986. The median range of blood cholesterol at which diet therapy was initiated was 6.21 to 6.70 mmol/L (240 to 259 mg/dL) in 1986, down from 6.72 to 7.21 mmol/L (260 to 279 mg/dL) in 1983; the median for drug therapy was 7.76 to 8.25 mmol/L. (300 to 319 mg/dL) in 1986 and 8.79 to 9.28 mmol/L (340 to 359 mg/dL) in 1983. In 1986, 87% of physicians surveyed felt that medical evidence warranted the recommended treatment levels set forth in the 1984 National Institutes of Health Consensus Conference on Lowering Blood Cholesterol. These changes indicate that by 1986, physicians were more convinced of the benefit of lowering high blood cholesterol levels and were treating patients accordingly. The data also suggest areas for continued educational initiatives.